The disclosure relates generally to gas turbine engines and, more particularly, to a fiber preform architecture for composite articles for gas turbine engines, such as composite fan containment cases, and methods of fabrication.
Gas turbine engines typically include high and low pressure compressors, a combustor, and at least one turbine. The compressors compress air, which is mixed with fuel and channeled to the combustor. The mixture is then ignited for generating hot combustion gases, and the combustion gases are channeled to the turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator.
Gas turbine engines used in aircraft have a fan with a hub, and fan blades are disposed for rotation about a central axis. When engines operate in various conditions, foreign objects may be ingested into the engine. More specifically, various types of foreign objects may be entrained in the inlet of a gas turbine engine, ranging from large birds, to hailstones, sand and rain. The foreign objects may impact a blade resulting in a portion of the impacted blade being torn loose from a rotor. Catastrophic damage can occur to the aircraft and its occupants if a broken fan blade is propelled radially outwardly from the rotating hub under centrifugal force and impacts on the aircraft fuselage.
In an attempt to prevent such damage, it is common to include a generally cylindrical fan containment case about the periphery for containing the fan blade and any foreign objects. Fan containment cases may also be subject to foreign object damage that causes the rotor blade to pierce an engine fan case resulting in cracks along an exterior surface of the engine fan case. Additionally, foreign object damage may cause a portion of the engine to bulge or deflect resulting in increased stresses along the entire engine fan case. A fan containment case is typically fabricated from a metallic material which results in an increased weight of the engine and therefore the airframe. Fan containment cases made of composite materials combine excellent impact resistance and damage tolerance properties with significant weight reduction relatively to the metal case.
Composite laminates made by textile fabric (ex. woven, braid) are known to have superior damage tolerance compared to unidirectional laminates, and such textile fiber preforms are suitable for fiber architecture of a fan containment case shell to obtain containment capability. However, known composite fabrication processes using textile fabric generally involve manual processes and are not cost effective. The recent development of automated fiber placement (AFP) machine enables an automated and more cost effective method of producing composite components. However, conventional fiber placement processes cannot utilize textile fabric and generate unidirectional laminates by placing the fiber bands comprising longitudinal fibers and a resin adjacent to each other.
It would therefore be desirable to provide a novel textile fiber preform for composite articles, such as a fan containment case, and method of fabrication that provides high impact resistance and superior damage tolerance, without increasing the overall weight.